1. Technical Field
The present invention relates to a method for preparing Te(O) in a low toxic form from toxic Te(IV) using metal-reducing bacteria and iron ions.
2. Description of the Related Art
Tellurium (Te) and its compounds are widely used in petroleum refining, electronic and photoelectronic industries, optics, glass and sensors (Sen, S. et al., Talanta 2009, 77 (5), 1567-1572; Tang, Z. et al. Science 2006, 314 (5797), 274-8; Turner, R. J. et al. Biotechnol. Adv. 2012, 30 (5), 954-963; Wang, X. et al. Bioresour. Technol. 2011, 102 (3), 3268-71). However, recently expanded use of Te has led to environmental contamination (Chasteen, T. G. et al. FEMS Microbiol. Rev. 2009, 33 (4), 820-32). In the environment, water soluble tellurite oxyanions (TeO32−, Te(IV)) are highly toxic to both eukaryotic and prokaryotic cells at concentrations as low as 1 μg/ml (Chasteen, T. G. et al. FEMS Microbiol. Rev. 2009, 33 (4), 820-32; Zannoni, D. et al. Adv. Microb. Physiol. 2007, 53, 1-71).
The redox chemistry of Te is crucial in governing mobility and toxicity. The elemental state of Te(O) is insoluble in water and has low bioavailability and toxicity. Therefore, the reduction of Te(IV) to insoluble and less toxic Te(O) is an effective strategy for relieving the high toxicity of Te(IV) in the environment. Several recent studies have shown that Te can be removed from aqueous solution via the reduction of Te(IV) to insoluble and low toxic forms (Turner, R. J. et al. Biotechnol. Adv. 2012, 30 (5), 954-963; Wang, X. et al. Bioresour. Technol. 2011, 102 (3), 3268-71; Taylor, D. E. Trends Microbiol. 1999, 7 (3), 111-5; Baesman, S. M. et al. Appl. Environ. Microbiol. 2007, 73(7), 2135-43).
The biogeochemical cycles of major and trace elements in the environment are driven by redox processes, which also affect the chemical species, bioavailability, toxicity, and mobility of the elements. Especially, the most abundant iron ion on the Earth's surface plays a particularly important role in environmental biogeochemistry. In fact, the soluble Fe(II) produced by reduction of iron oxide and Fe-bearing minerals by various biogeochemical reactions can act as a powerful reducing agent in a variety of abiotic redox processes (Liger, E. et al. Geochim. Cosmochim. Acta 1999, 63 (19-20), 2939-2955).
The disclosures of all cited articles and patent publications referred to in this specification are incorporated herein by reference in their entirety to enable a person having ordinary knowledge in the art to more clearly understand the technical field and context of the present invention.